1. Field of the Invention
The present invention relates to a system and method for remote access to High bit-rate Digital Subscriber Line (HDSL) circuitry configuration and performance data and, more specifically, to a system and method of adding equipment to existing HDSL circuit chassis to allow economical remote access to HDSL circuit cards' craft access ports.
2. Description of the Related Art
Historically the telephone industry has used various digital encoding techniques to multiplex multiple subscriber circuits onto one or two wire pairs. Widely utilized DS-1 (T-1) encoding provides twenty-four subscriber lines on two unconditioned copper twisted pair wires. T-1 has operational limitations though, especially when spanning long distances between the telephone supplier and the end user. T-1 is limited to approximately eight hundred feet of distance between source and destination before a repeater must be used. A limit of ten repeaters can be used on one span, which limits the total distance between the source of the T-1 line and the ultimate destination to under nine thousand feet. Both the limited range of use and the extra expense of repeaters have prompted the telephone industry to look to other methods of encoding.
High bit-rate Digital Subscriber Line (HDSL) transceivers encode DS-1 into a multi-bit stream that can be sent on one or two twisted pairs up to twelve thousand feet without a repeater. Most DS-1 circuits today are delivered using HDSL. The HDSL circuit cards have built in diagnostic and configuration capabilities, allowing units to be soft-configured for various modes of operation. The units also measure and record data relating to their performance, such as error rates and signaling margin, collectively called Performance Monitoring (PM) data. Configuration and PM data are accessed by a skilled technician using an ACSII terminal connected through a standard (9-pin) RS-232 serial port located on the face plate of the HDSL circuit card. Data collected in this manner is non-intrusive, i.e. it does not disrupt a working circuit.
Up to twenty-eight HDSL circuit cards are housed in a twenty-three inch chassis. Typical telephone offices have 4-50 (or more) of these chassis, providing HDSL service to over fourteen hundred customers. To access the configuration and recorded performance data on these circuit cards, a technician is required to physically connect an ASCII terminal to the circuit card. This is a costly operation in terms of man-hours required to access and collect PM data. Additional costs can arise from a loss of revenue due to delays in diagnosing a defective DS-1 circuit since a technician is not immediately available on location to physically connect a terminal to the defective circuit card.
The first HDSL systems deployed in the telephone industry did not allow for remote test access capabilities. As mentioned above, the only means to provision, test or retrieve historical data from the HDSL circuit card was via a serial port on the faceplate of each circuit card. Newer HDSL systems incorporate remote access features, but these are vendor specific and require replacement of an entire shelf as well as the individual HDSL circuit cards. With over 10 million legacy HDSL circuit cards still in use, replacing each individual circuit card is financially impractical. What is needed is a way of modifying existing HDSL systems to provide remote access to some or all craft access ports on an individual HDSL circuit card in an HDSL chassis.